Analysis of HIV promoter mutants in vitro indicates the existence of two overlapping DNA control elements. One is a positive element located in the "initiator" region (near the RNA start site) that is required for promoter activity.The other, a negative element, is the DNA-binding site for LBP-1 which has been implicated as playing a role both in inducing attenuated transcripts and in repressing initiation of viral RNA synthesis. Here, the investigator proposes to characterize the structure and transcriptional activities of these two proteins and to analyze how they function through overlapping regions of the promoter.To obtain the gene for the LBP-1 factor, the investigator plans to use peptide sequence data obtained by microsequencing of purified protein.She proposes to use these genes to develop immunological reagents and probes specific to each factor in order to study their structure, expression and the mechanism of transcriptional activation by hSNF-2 (the initiator binding protein) and repression or attenuation by LBP-1.